Date: Sat, 17 Feb 2007 08:31:21 -0000 (GMT) From: aji@katuns.org To: freebsd-questions@FreeBSD.org Cc: freebsd-doc@FreeBSD.org Subject: softc And device_get_softc(dev) Message-ID: <41759.122.167.57.52.1171701081.squirrel@katuns.org>
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hi
My name is Aji Abraham, now working with device drivers. the word
"softc" and the function "device_get_softc(dev)" getting confuse me a
lot. am listing some query below .. pls help me ..
Q1 In a free BSD driver Code, there are two device depended structures
struct xx_softc {
.......
......
};
struct xx_if_softc {
.......
......
};
sizeof(struct xx_softc ) is 68
sizeof(struct xx_if_softc ) is 1186
And in device attach function
xx_attach(dev){
struct xx_softc *sc;
struct xx_if_softc *if_sc;
sc_if = device_get_softc(dev);
sc = device_get_softc(device_get_parent(dev));
sc_if-> .....
sc-> ....
.......
......
}
Both allocation uses the same function. How it possible ? can we access
all structure member ?
Regards
Aji Abraham
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